using KumiScript.Interpreter;

namespace KumiScript.Reader
{
    public class ParserListVisitor : ITokenVisitor
    {
        Parser _parser;
        public ParserListVisitor(Parser parser)
        {
            _parser = parser;
        }

        public Expression VisitAtom(AtomToken atom)
        {
            return atom.ToExpression();
        }

        public Expression VisitString(StringToken str)
        {
            return str.ToExpression();
        }

        public Expression VisitEoF(EndOfFileToken eof)
        {
            throw new ParserUnexpectedEndOfFileException("Expected ')' before end of file.");
        }

        public Expression VisitParen(ParenthesisToken paren)
        {
            if (!paren._leftParen)
                return null;    //TODO: some other way of throwing it back

            List<Expression> list = new List<Expression>();
            Expression item = _parser.NextExpressionCC(this);

            while (item is not null)
            {
                list.Add(item);
                item = _parser.NextExpressionCC(this);
            }

            return ListFactory.MakeList(list);
        }

        public Expression VisitSpecial(SpecialToken spec)
        {
            if (spec._value == '\'')
                return _parser.NextExpressionCC(new ParserQuoteVisitor(_parser));
                
            throw new NotImplementedException();
        }
    }
}